Method and apparatus for sending a channel quality indication via a shared channel

ABSTRACT

A method and apparatus for sending a channel quality indication (CQI) via a shared channel while a wireless transmit/receive unit (WTRU) is in a Cell_FACH state without having a dedicated channel allocated for the WTRU are disclosed. A WTRU performs a measurement of at least one parameter and generates a CQI based on the measurement. The WTRU then transmits the CQI via a random access channel (RACH). The CQI may be transmitted using an RACH preamble. A plurality of signature sequences may be divided into a plurality of groups. The WTRU may select one group based on the CQI and randomly select a signature sequence among signature sequences in the selected group for transmitting the RACH preamble. The CQI may be appended to the RACH preamble. The CQI may be transmitted via a control part or a data part of the RACH message.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application No.60/862,522 filed Oct. 23, 2006, 60/888,146 filed Feb. 5, 2007, and60/908,484 filed Mar. 28, 2007, which are incorporated by reference asif fully set forth.

FIELD OF INVENTION

The present invention is related to wireless communications.

BACKGROUND

A wireless transmit/receive unit (WTRU) in a universal terrestrial radioaccess network (UTRAN) may be in either an idle state or a connectedstate. While the WTRU is in a connected state, based on WTRU mobilityand activity, the UTRAN may direct the WTRU to transition betweenCell_PCH, URA_PCH, Cell_FACH, and Cell_DCH states. User planecommunication between the WTRU and the UTRAN is only possible while theWTRU has a radio resource control (RRC) connection to the UTRAN.

The Cell_DCH state is categorized by dedicated channels in both uplinkand downlink. On the WTRU side, this corresponds to continuoustransmission and reception and may be demanding on user powerrequirements.

As defined in Release 6 of the Third Generation Partnership Project(3GPP) specifications, the Cell_FACH state does not use dedicatedchannels and thus allows better power consumption at the expense of alower uplink and downlink throughput. While in the Cell_FACH state,uplink communication is achieved through a random access channel (RACH)while downlink communication is through a shared transport channel,(e.g., a forward access channel (FACH)), mapped to a secondary commoncontrol physical channel (S-CCPCH). The Cell_FACH state is suited forsignalling traffic, (e.g., transmission of cell update and UTRANregistration area (URA) update messages), and for applications requiringvery low uplink throughput.

While in the Cell_FACH state, the WTRU may perform signal measurementsand/or traffic volume measurements (TVM) as specified in the measurementcontrol information. The signal measurement is used by the WTRU for cellreselection. The TVM is reported to the UTRAN within a measurementreport based on criteria specified on the measurement controlinformation. The measurement report is sent via the RACH.

The RACH is based on a slotted-Aloha mechanism with an acquisitionindication. Before sending an RACH message, a WTRU attempts to acquirethe channel by sending a short preamble (made up of a randomly selectedsignature sequence) in a randomly selected access slot. Aftertransmitting the RACH preamble, the WTRU waits for an acquisitionindication from the UTRAN. If no acquisition indication is received, theWTRU ramps up the transmit power for the RACH preamble and retransmitsthe RACH preamble, (i.e., sends a randomly selected signature sequencein a selected access slot). If an acquisition indication is received,the WTRU has effectively acquired a channel, and may transmit an RACHmessage. The initial transmit power for the RACH preamble is set basedon an open loop power control technique, and the ramp-up mechanism isused to further fine-tune the WTRU transmit power.

It has been proposed to use high speed downlink packet access (HSDPA) ina Cell_FACH state. HSDPA is a feature that was introduced in Release 5of the third generation partnership project (3GPP) specifications. HSDPAoperates in a Cell_DCH state. HSDPA makes better use of the downlinkshared capacity by using three key concepts: adaptive modulation andcoding (AMC), retransmissions using a hybrid automatic repeat request(HARQ) scheme, and Node-B scheduling.

Every two (2) milliseconds, the Node-B schedules transmissions on thehigh speed downlink shared channel (HS-DSCH) based on information theNode-B collects from the WTRUs and the status of the downlink buffers.In addition, the Node-B tailors the transmission bit rates to thespecific WTRUs by adapting the MCS, transport block size, etc. TheNode-B may transmit at a higher data rate to those WTRUs which perceivefavorable channel conditions, and a lower data rate to those WTRUs thatperceive unfavorable channel conditions, (e.g., at the cell edge).

For the HSDPA operations, the Node-B needs channel quality indication(CQI) and positive-acknowledgement (ACK)/negative-acknowledgement (NACK)feedback from the WTRUs. The CQI is an index into a table which providesthe maximum MCS that the WTRU may support. The CQI is sent periodicallywith periodicity determined by the UTRAN. The ACK/NACK feedback is forthe HARQ process. The ACK/NACK information is only provided in responseto a packet being received on the downlink.

In Release 6 of the 3GPP specifications, the CQI and ACK/NACKinformation are transmitted via a high speed dedicated physical controlchannel (HS-DPCCH). Each WTRU is assigned a separate HS-DPCCH and as aresult a WTRU may easily provide the feedback information. Moreover, theHS-DPCCH is power controlled using an offset to the uplink dedicatedphysical control channel (DPCCH), for which close loop power control isperformed. The information on the HS-DPCCH is heavily coded to aid indetection. As more and more WTRUs use HSDPA, the number of feedbackcontrol channels increases. Even if these are power controlled, thefeedback information may cause an uplink noise rise, reducing thecapacity available for other uplink transmissions.

If HSDPA is to be used in a Cell_FACH state, the main problem is a lackof dedicated uplink channel to transmit the CQI and ACK/NACKinformation. Without the CQI and ACK/NACK information, the advantages ofHSDPA are significantly reduced. 3GPP Release 6 specifications do notprovide support for optimal MCS selection and scheduling for the HS-DSCHin a Cell_FACH state.

Therefore, it would be desirable to provide a method and apparatus forproviding CQI information via a shared channel in a Cell_FACH state.

SUMMARY

A method and apparatus for sending a CQI via a shared or common channelwhile a WTRU is in a Cell_FACH state without having a dedicated channelallocated for the WTRU are disclosed. A WTRU performs a measurement ofat least one parameter and generates a CQI based on the measurement. TheWTRU then transmits the CQI via an RACH. The CQI may be transmittedusing an RACH preamble. A plurality of signature sequences may bedivided into a plurality of groups. The WTRU may select one group basedon the CQI and randomly select a signature sequence among signaturesequences in the selected group for transmitting the RACH preamble. TheCQI may be appended to the RACH preamble. The CQI may be transmitted viaa control part or a data part of the RACH message. The RACH message maybe an RRC measurement report including CQI transmission. The CQIreporting may be triggered by successful decoding of the HS-SCCHtransmission.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description of a preferred embodiment, given by way of exampleand to be understood in conjunction with the accompanying drawingswherein:

FIG. 1 is a block diagram of an example WTRU;

FIG. 2 shows a CQI appended at the end of an RACH preamble;

FIG. 3 shows an example of the CQI carried in the RACH control message;

FIG. 4 shows an example of the CQI carried in the RACH header in an RACHmessage;

FIG. 5 shows an example two-tiered CQI structure; and

FIG. 6 shows a CQI reporting triggering example.

DETAILED DESCRIPTION OF THE EMBODIMENTS

When referred to hereafter, the terminology “WTRU” includes but is notlimited to a user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a computer, or any other type of user device capable ofoperating in a wireless environment. When referred to hereafter, theterminology “Node-B” includes but is not limited to a base station, asite controller, an access point (AP), or any other type of interfacingdevice capable of operating in a wireless environment.

It should be noted that although the embodiments will be described withreference to 3GPP high speed downlink packet access (HSDPA), the presentinvention is applicable to any wireless communication system wherechannel quality feedback information is required to be transmitted via ashared/common channel.

FIG. 1 is a block diagram of an example WTRU 100. The WTRU 100 mayinclude a measurement unit 102, a CQI generator 104, and a transceiver106. It should be noted that the WTRU 100 in FIG. 1 is provided as anexample, not as a limitation, and the WTRU 100 may include any otherconventional processing components necessary for wireless transmissionand reception. The measurement unit 102 performs a measurement of atleast one predetermined parameter to provide an estimate of the channelquality perceived by the WTRU 100.

The measurement parameter may be a downlink transport channel blockerror rate (BLER) while the WTRU 100 is in a Cell_FACH state. A highBLER may be interpreted that the downlink transmission rate is too high.The measurement parameter may be a path loss measured on a downlinkreference channel, (e.g., a common pilot channel (CPICH)). A high pathloss in the downlink may be interpreted as an indication that thedownlink transmission rate is too high. The measurement parameter may bethe number of preamble ramp-ups required before receiving an acquisitionindication on an acquisition indication channel (AICH). For example, ifthe WTRU 100 requires many RACH preamble transmit power ramp-ups, or ifthe RACH transmission fails, the WTRU 100 may interpret that channelconditions are poor and ask for a reduction in the downlink transmissionrate. The measurement parameter may be a received power on a CPICH, ahigh speed shared control channel (HS-SCCH), or any other downlinkreference channel. By providing an indication of this power, the Node-Bmay estimate the path loss and increase or decrease the downlinktransmission rate accordingly. The measurement parameter may be anestimate of a signal-to-noise ratio (SNR) measured on any downlinkreference channel, (e.g., CPICH), where the noise comprises a thermalnoise and an interference from neighbouring cells that cannot becancelled by the WTRU. The measurement parameter may be CPICH Ec/N0,(i.e., CPICH received signal code power (RSCP)/received signal strengthindicator (RSSI)) or primary common control physical channel (PCCPCH)RSCP converted into HS-DPDCH measurement adding RSSI. Alternatively,HS-SCCH power may be measured.

The CQI generator 104 outputs a CQI based on the measurement(s), (i.e.,the CQI is an encoded version of the measurement). One or a combinationof any of the above WTRU measurements may be mapped into a CQI value,(e.g., an index to a look-up table), and sent to the Node-B via one ofthe feedback mechanisms that will be described in detail below. The CQIvalue may be sent to an RRC layer for reporting at the RRC layer. TheCQI value may be filtered at the RRC layer. In performing the mapping,the WTRU 100 may also take into account its own receiver capabilities togenerate a CQI.

The CQI is not necessarily a straight encoding of the measurements, butmay also be an estimate of the transport block size or a maximum datarate that the WTRU 100 may support based on its receiver design and themeasured quantities, (i.e., the CQI may be an encoded version of atransport block size or the maximum data rate that the WTRU may supportto maintain a target block error rate (BLER). The maximum transportblock size or the maximum data rate that may be supported by the WTRU isformatted and encoded into an index value, (i.e., CQI value).

Alternatively, the CQI may be a relative up or down command generatedbased on the measurement. For example, the relative up/down command maybe generated based on a transport block size that the WTRU may supportto maintain a target BLER. For instance, the WTRU 100 may decide thatthe channel quality is very poor and ask for a reduction in downlinktransmission rate to the next lower level. In this case, the granularityof the control may be more than one step, (e.g., up 3 levels, down 4levels). The relative up or down command may indicate an increase ordecrease in maximum transport block size that the WTRU 100 may receivewith an adequate BLER, or an increase or decrease a measurement value,(e.g., in dB), on a channel, (e.g., path loss).

The CQI may have a multi-tiered structure. FIG. 5 shows an exampletwo-tiered CQI structure. It should be noted that FIG. 5 is provided asan example, not as a limitation, and any other CQI structure may beimplemented. In this example, the CQI value is encoded with five (5)bits. The first two most significant bits (MSBs) are used as a coarseCQI and the three least significant bits (LSBs) are used as a fine CQIwithin each coarse CQI range. The CQI reporting via the RRC measurementreporting may be used for sending the coarse CQI (slow update), andphysical layer (L1) procedure may be used for sending the fine CQI (fastupdate). In a slowly varying channel condition, the coarse CQI may beused, while if the rate of change of the CQI is faster, the CQI may bereported via L1-based CQI reporting procedure.

Once the CQI is generated, the transceiver 106 transmits the CQI to theNode-B. Since there is no dedicated control channel assigned to the WTRU100 in a Cell_FACH state, the transceiver 106 sends the CQI informationvia an RACH or any other contention-based channel that requires the WTRUto first acquire the channel before initiating transmission.

The transmission of the CQI provides fresh and appropriate linkperformance predictors for transmissions on the HS-DPDCH. The CQI may besent when the WTRU has previously been in a URA_PCH or Cell_PCH mode andperformed no measurements and therefore no measurement is available tothe UTRAN. The CQI may be reported when the WTRU has sent at least onemeasurement value to the UTRAN but is yet to receive any downlinktransmission. The CQI may be reported when the WTRU has been receivingtransmissions for some time, but the measurements become stale. In thelast two cases, the amount of measurement controls required on theHS-DSCH is reduced.

Embodiments for sending the CQI are disclosed hereinafter. In accordancewith a first embodiment, the WTRU 100 sends the CQI information using anRACH preamble. Conventionally, a WTRU selects a RACH preamble signaturesequence randomly among a plurality of signature sequences. Inaccordance with the first embodiment, the signature sequences aredivided into a plurality of groups. The WTRU 100 select one group basedon the CQI and then selects a signature sequence randomly among thesignature sequences in the selected group. The selection of thesignature sequence is not completely random, but depends on the CQI. Forexample, if a two (2)-bit CQI is used and total 16 signature sequencesare divided into four groups, each with four unique signature sequences,the CQI may be used to select one of the four (4) groups, and one of thefour signature sequences in the selected group is randomly selected.Upon decoding the signature sequence at the Node-B, the Node-Bcross-references the signature sequence number to determine the groupand the transmitted CQI.

If the number of CQI indices exceeds 16, the number of conventional16-bit preamble signature sequences may be increased from 16 to 2^(k)(where k>4), and rather than repeating the selected signature sequence256 times in every preamble, the WTRU 100 may repeat the new signaturesequence (256/(2^(k-4))) times.

Alternatively, a CQI may be appended at the end of the RACH preamble.FIG. 2 shows a CQI 206 appended at the end of an RACH preamble 202. Inthis example, the RACH preamble transmission includes 256 repetitions of16 bit signature sequence 204 and a CQI 206. When the Node-B detects thepreamble sequence 202, the Node-B retrieves the CQI 206 at the end ofthe preamble sequence 202 and sends an acquisition indication. The WTRUidentity (ID) may be determined when the Node-B decodes the RACHmessage. Alternatively, the WTRU ID may also be appended at the end thepreamble. This allows transmitting all required information in thepreamble without needing a subsequent RACH message transmission.

In accordance with a second embodiment, a CQI is sent through thecontrol part of the RACH message. FIG. 3 shows an example RACH time slotformat. A 10 ms RACH radio frame 300 includes 15 time slots 302. Eachtime slot 302 includes a data part 310 and a control part 320 that aretransmitted in parallel. Conventionally, the control part 320 carriespilot bits 322 and TFCI bits 324. In accordance with the secondembodiment, the CQI 326 is included in the control part 320.

In accordance with a third embodiment, the CQI is sent through the datapart 310 of the RACH message. FIG. 4 shows an example RACH header 410and an MAC service data unit (SDU) 420 in an RACH message 400. The CQI412 is included in the RACH header 410. In order to include the CQI 412in the RACH header 410, the physical layer provides the CQI 412 to theMAC layer (MAC-c/sh layer), and the MAC layer adds the CQI 412 in theMAC header 410. The signalling between the physical layer and the MAClayer may be implemented, for example, through a modified PHY-Status-INDprimitive.

In accordance with a fourth embodiment, the CQI may be sent through anRRC message, (e.g., measurement report message). The CQI is sent to theRRC layer of the WTRU to be included in the RRC message. The CQI mayoptionally be filtered by the RRC layer before sending the RRC message.

As the capacity of the physical RACH (PRACH) is limited, rules aredefined for determining when transmission of the CQI should take place.A WTRU may transmit the CQI when the WTRU has an MAC SDU to transmit viathe RACH, (i.e., opportunistic transmission). The CQI may be transmittedwithin the RACH preamble or RACH message as disclosed above.

Opportunistic transmission may not be sufficient because it depends onthe need to transmit information on the uplink which is not necessarilycorrelated to downlink transmissions. To enable CQI reporting in theabsence of uplink transmission on the RACH, the WTRU may transmit theCQI, even if the WTRU does not need to send an MAC SDU, (i.e., CQIstand-alone transmission). The TFCI field may be used to signal theNode-B that the RACH transmission is a CQI stand-alone transmission. Forthe CQI stand-alone transmissions, a CQI may be appended to the RACHpreamble as shown in FIG. 2, or may be transmitted in the control partor in the data part of the RACH message.

Alternatively, triggering criteria may be defined for transmission ofthe CQI, (i.e., stand-alone CQI transmissions). A CQI may be transmittedperiodically. The WTRU may send the CQI periodically once the WTRU hasan active HSDPA connection in a Cell_FACH state. The WTRU maycontinuously monitor the channel condition, and send the CQI at periodicintervals. The rate of CQI reporting is provided to the WTRU as aconfiguration parameter. The CQI may be reported with a random offset toreduce probability of collision between WTRUs.

A CQI may be polled by the Node-B. For example, the WTRU may transmit aCQI upon reception of data on the downlink. The Node-B may select a lowMCS or transmit no data at all on this initial downlink transmission(thus reducing interference) if the Node-B does not have fresh CQIinformation. The downlink transmission may be a transmission on anHS-SCCH destined to the WTRU. In this case, the WTRU monitors theHS-SCCH, and triggers the transmission of the CQI when the WTRUsuccessfully decodes its address, (i.e., HSDPA radio network temporaryidentity (H-RNTI)), on the HS-SCCH transmission in the downlink.

The WTRU may send a CQI upon significant change of channel conditions.The WTRU may transmit a CQI when the difference between the current CQI(or average CQI) and the last reported CQI exceeds a pre-determinedvalue. The WTRU, (e.g., RRC), is configured with a CQI delta. Every timethe measured CQI value exceeds the previous CQI value by the CQI deltafor a predefined period of time, a CQI reporting is triggered.

The WTRU may send a CQI at the start of an HSDPA connection in aCell_FACH state. The WTRU may continuously monitor the channelcondition, but the CQI may be sent after an RRC CONNECTION SETUP messageis received for the HSPDA channel.

The range of the CQI may be divided into multiple CQI levels with CQIthresholds, and the WTRU may send a CQI based on comparison of themeasured (or filtered) CQI to the CQI thresholds. If the measured (orfiltered) CQI crosses a CQI threshold, (i.e., changes CQI level), andremains at the new CQI level for a predefined period of time, a CQIreporting is triggered. FIG. 6 illustrates a CQI triggering examplebased on comparison to the CQI thresholds. It should be noted that FIG.6 is provided as an example, not as a limitation, and the CQI range maybe divided into any number of levels. In this example, two CQIthresholds are configured and the CQI range is divided into threelevels, (CQI1, CQI2, and CQI3). Initially, the measured CQI belongs toCQI1 level. At time A, the measured CQI changes to the second level,CQI2. At this time, a timer is set to trigger the CQI reporting. Themeasured CQI remains in the CQI2 level until the timer expires, andtherefore a CQI reporting is triggered at the expiration of the timer.At time B, the measured CQI changes to CQI1 level, and the timer is setagain. The measured CQI changes to CQI2 level before the timer expires.Therefore, a CQI is not sent at this time. At time C, the measured CQIchanges to CQI3 level, and the timer is set. The measured CQI remains inthe CQI3 level until the timer expires, and a CQI reporting is triggeredat the expiration of the timer.

The CQI reporting may be triggered based on certain WTRU actions. Forexample, the CQI may be sent when the WTRU changes to the Cell_FACHstate and/or upon cell reselection in either of the Cell_FACH, Cell_PCH,and URA_PCH states.

The CQI reporting may be triggered based upon downlink reception, (e.g.,sent when the WTRU fails to decode the downlink reception), and the CQImay be sent together with RRC and/or radio link control (RLC) ACK/NACKinformation. The CQI reporting triggering rate may be adjusted based onNACK counts. The reporting rate is increased as the NACK counts increaseand the reporting rate is decreased as the ACK counts increases.

The CQI reporting may be triggered based on HARQ BLER, when no data orcontrol information, (i.e., HS-SCCH transmissions), is received whensuch is expected, based on transport block BLER.

The CQI reporting may be triggered based on HS-SCCH reception. Once theWTRU successfully decodes an HS-SCCH transmission, the WTRU expects datatransmission on the associated HS-PDSCH. After correctly decoding aHS-SCCH transmission, if the WTRU is no table to recover the HS-PDSCHtransmission, the CQI reporting may be triggered. This triggeringmechanism may be based on an averaging window, such that the CQIreporting is triggered upon M occurrences out of N observances. The Mand N may be hardcoded or network configurable.

Alternatively, the CQI reporting may be triggered by counting the numberof successful HS-SCCH transmissions (K) in an observation window. Theobservation window is started with the first decoding of the HS-SCCHtransmission with a new data indicator indicating a new transport block.The observation window should be large enough to include allretransmissions that are expected for each transmitted packet. Theobservation window may be terminated at the arrival of the next HS-SCCHtransmission with a new data indicator. The CQI is triggered when K isless than the maximum number of retransmissions configured for HSDPA inCell_FACH. The value of K and the observation window size may be networkconfigurable. The trigger may be based on an averaging window.

Alternatively, the CQI reporting may be triggered after correctlydecoding the HS-SCCH transmission and recovering the transmitted packeton the HS-PDSCH after L retransmissions, where L is less than themaximum number of retransmissions configured for HSDPA in Cell_FACH. Theparameter L may be hardcoded or network configurable. This event impliesthat current MCS is too conservative. The trigger may be based on anaveraging window.

The CQI reporting may be triggered based on inactivity on the HS-SCCH.The WTRU may start a timer after decoding a HS-SCCH transmission andtrigger the CQI reporting if the WTRU fails to receive any HSDPAtransmission until the timer expires. The timer value may be hardcodedor network configurable.

The threshold values and timer values disclosed hereinbefore may bedefined as part of the system information. The threshold and timervalues may be redefined. In order to reduce the downlink signaling loadto specify these new threshold and timer values via RRC signaling, thethresholds and timer values may be changed autonomously by the WTRUbased on the RRC and/or RLC ACK/NACK information. The threshold valuesmay be linear, asymmetric, or logarithmic (having finer granularity forcertain levels at the expense of others). The threshold values may bechanged autonomously by the WTRU based on the HARQ BLER.

The CQI reporting may be controlled by downlink control signalling in aCell_FACH state. The downlink control signalling may be sent via anHS-SCCH, an MAC-hs header, a physical layer signal, an L2 controlchannel in the downlink, etc.

Transmission of the CQI via the RACH may be configured by the higherlayer signaling, (e.g., layer 3 signaling). Such configuration includesthe signature sequences that the WTRU should use to transmit the RACHpreamble, the time slot format, scrambling and channelization codes thatthe WTRU should use to transmit the PRACH, and the like.

The network may learn about the capabilities of different WTRUs, anddetermine whether a WTRU is capable of sending a CQI through thePRACH/RACH. The network may send configuration parameters to the WTRUbased on the WTRU capability. The configuration parameters may be sentby adding new information elements (IEs) to a conventional systeminformation block (SIB) in a BCCH, defining a new SIB (and schedule) inthe BCCH, or adding an IE to the RRC CONNECTION SETUP message when theHSDPA channel is set up. The new measurements may fall under thecategory of “Quality Measurements” and may be applied to WTRUs inCell_FACH state. The configuration parameters includes a method forsending the CQI information, (over RACH, over a L1-based approach, usingcoarse or fine CQI, and the like), CQI reporting parameters, CQIfiltering coefficients (for layer 3 filtering of CQI value), CQIreporting criteria, (i.e., timer and threshold values), and the like.

For backward compatibility, the Node-B may be made aware that a WTRU issending a CQI through a RACH, (i.e., the RACH transmission includes aCQI). In order to distinguish the RACH transmissions including a CQI,new signature sequences may be defined, or certain signature sequencesare reserved, for CQI reporting purposes so that the Node-B maydistinguish an RACH transmission including a CQI and an RACHtransmission not including a CQI. Alternatively, one or several valuesfor the TFCI field of the control part of the RACH message, (or anyfield in the RACH header), may be reserved for RACH transmissions thatinclude a CQI. As another alternative, a set of scrambling andchannelization codes may be reserved for RACH transmissions that includea CQI.

The present invention is applicable to a WTRU in Cell_PCH and URA_PCHstates. In these states, the measurements used for CQI calculation neednot be updated continually, but may be monitored upon reception of apaging indicator channel (PICH) in anticipation of switching to theCell_FACH state. This would allow the WTRU to stay in a power savingstate, and only make measurements when needed.

Although the features and elements are described in the preferredembodiments in particular combinations, each feature or element can beused alone without the other features and elements of the preferredembodiments or in various combinations with or without other featuresand elements. The methods or flow charts provided may be implemented ina computer program, software, or firmware tangibly embodied in acomputer-readable storage medium for execution by a general purposecomputer or a processor. Examples of computer-readable storage mediumsinclude a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as internal hard disks and removable disks, magneto-optical media,and optical media such as CD-ROM disks, and digital versatile disks(DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) module.

1. A method for sending a channel quality indication (CQI) via a sharedchannel, the method comprising: a wireless transmit/receive unit (WTRU)performing a measurement of at least one parameter; the WTRU generatinga CQI based on the measurement; and the WTRU transmitting the CQI via acontention-based uplink shared channel.
 2. The method of claim 1 whereinthe contention-based uplink shared channel is a random access channel(RACH).
 3. The method of claim 2 wherein the CQI is transmitted using aRACH preamble.
 4. The method of claim 3 wherein a plurality of signaturesequences are divided into a plurality of groups, and the WTRU selectsone group based on the CQI and randomly selects a signature sequenceamong signature sequences in the selected group for transmitting theRACH preamble.
 5. The method of claim 3 wherein the CQI is appended tothe RACH preamble.
 6. The method of claim 5 wherein a WTRU identity isappended to the RACH preamble.
 7. The method of claim 2 wherein the CQIis transmitted via at least one of a control part of an RACH message ora data part of the RACH message.
 8. The method of claim 7 wherein atleast one value of a transport format combination index (TFCI) field isreserved for the RACH message that contains a CQI, so that a Node-B maydistinguish a RACH transmission including the CQI from a RACHtransmission not including the CQI.
 9. The method of claim 2 wherein theCQI is transmitted along with a RACH medium access control (MAC) servicedata unit (SDU).
 10. The method of claim 9 wherein the CQI is signaledfrom a physical layer to a MAC layer via a PHY-Status-IND primitive. 11.The method of claim 2 wherein a set of signature sequences are reservedfor transmitting the CQI via the RACH, so that a Node-B may distinguisha RACH transmission including the CQI from a RACH transmission notincluding the CQI.
 12. The method of claim 2 wherein a set ofchannelization and scrambling codes are reserved for transmitting theCQI via the RACH, so that a Node-B may distinguish an RACH transmissionincluding the CQI from a RACH transmission not including the CQI. 13.The method of claim 2 wherein transmission of the CQI via the RACH isconfigured by higher layer signaling.
 14. The method of claim 1 whereinthe measurement used for generating the CQI is at least one of ameasured block error rate (BLER), a path loss on a downlink referencechannel, a signal-to-noise ratio (SNR) measured on the downlinkreference channel, common pilot channel (CPICH) Ec/N0, the number ofrandom access channel (RACH) preamble ramp-ups required for RACHtransmission, or a received power on the downlink reference channel. 15.The method of claim 1 wherein the CQI is an encoded version of at leastone of a transport block size or a maximum data rate that the WTRU cansupport to maintain a target block error rate (BLER).
 16. The method ofclaim 1 wherein the CQI is a relative up/down command.
 17. The method ofclaim 16 wherein the relative up/down command is generated based on atleast one of a transport block size or a maximum data rate that the WTRUcan support to maintain a target block error rate (BLER).
 18. The methodof claim 1 wherein the WTRU transmits the CQI periodically.
 19. Themethod of claim 18 wherein the CQI is sent with a random offset toreduce probability of collision between WTRUs.
 20. The method of claim 1wherein the WTRU transmits the CQI in response to a downlinktransmission from a Node-B.
 21. The method of claim 20 wherein theNode-B uses a low modulation and coding scheme (MCS) for the downlinktransmission.
 22. The method of claim 20 wherein the Node-B transmits nodata on the downlink transmission.
 23. The method of claim 1 wherein theWTRU transmits the CQI on a condition that the WTRU successfully decodesa high speed shared control channel (HS-SCCH) transmission.
 24. Themethod of claim 23 wherein the WTRU sends the CQI via a radio resourcecontrol (RRC) measurement report.
 25. The method of claim 1 wherein theWTRU transmits the CQI on a condition that a change of channel conditionexceeds a predetermined threshold for a predetermined period of time.26. The method of claim 1 wherein a CQI range is divided into multipleCQI levels with CQI thresholds, and the CQI is sent on a condition thatthe CQI crosses a CQI threshold and remains at a new CQI level for apredefined period of time.
 27. The method of claim 1 wherein the WTRUtransmits the CQI on a condition that the CQI is in a certain region ofCQI statistics.
 28. The method of claim 1 wherein the WTRU transmits theCQI based on control information received from a Node-B.
 29. The methodof claim 28 wherein the control information is transmitted to the WTRUvia at least one of a high speed shared control channel (HS-SCCH), amedium access control (MAC) header, a physical layer signaling, a layer2 control signaling, a connection setup message, or a broadcast controlchannel (BCCH).
 30. The method of claim 1 wherein the CQI is sent via aradio resource control (RRC) message at an RRC layer.
 31. The method ofclaim 30 wherein the CQI is filtered at the RRC layer.
 32. The method ofclaim 1 wherein the CQI has a multi-tiered structure so that a coarseCQI and a fine CQI are separately transmitted.
 33. The method of claim32 wherein the coarse CQI is sent via a radio resource control (RRC)message, and the fine CQI is sent via a physical layer (L1) signaling.34. The method of claim 1 wherein the CQI is sent at a start of a highspeed downlink packet access (HSDPA) connection in a Cell_FACH state.35. The method of claim 1 wherein the CQI is sent on a condition thatthe WTRU changes to a Cell_FACH state.
 36. The method of claim 1 whereinthe CQI is sent in response to cell reselection on a condition that theWTRU is in a Cell_FACH state, a Cell_PCH state, or a URA_PCH state. 37.The method of claim 1 wherein the CQI is sent on a condition that theWTRU fails to decode a downlink transmission.
 38. The method of claim 37wherein a CQI reporting rate is adjusted based on negativeacknowledgement (NACK) and positive acknowledgement (ACK) counts. 39.The method of claim 1 wherein the CQI is sent on a condition that nodata or control information is received on a condition that such isexpected.
 40. The method of claim 1 wherein the CQI is sent, in responseto correctly decoding a high speed shared control channel (HS-SCCH)transmission, on a condition that the WTRU is not able to recover a highspeed physical downlink shared channel (HS-PDSCH) transmission.
 41. Themethod of claim 1 wherein the CQI is sent in response to unsuccessfullydecoding a high speed shared control channel (HS-SCCH) transmission Ktimes in an observation window.
 42. The method of claim 1 wherein theCQI is sent in response to correctly decoding a high speed sharedcontrol channel (HS-SCCH) transmission and recovering a packet on a highspeed physical downlink shared channel (HS-PDSCH) in response to Lretransmissions.
 43. The method of claim 1 wherein the CQI is sent on acondition that the WTRU fails to receive a high speed downlink packetaccess (HSDPA) transmission for a predetermined period of time inresponse to decoding a high speed shared control channel (HS-SCCH)transmission.
 44. The method of claim 1 wherein the WTRU changesparameters for sending the CQI autonomously based on radio resourcecontrol (RRC) and radio link control (RLC) positive acknowledgement(ACK)/negative acknowledgement (NACK) information.
 45. A wirelesstransmit/receive unit (WTRU) for sending a channel quality indication(CQI) via a shared channel, the WTRU comprising: a measurement unit forperforming a measurement of at least one parameter; a CQI generator forgenerating a CQI based on the measurement; and a transceiver fortransmitting the CQI via a contention-based uplink shared channel. 46.The WTRU of claim 45 wherein the contention-based uplink shared channelis a random access channel (RACH).
 47. The WTRU of claim 46 wherein theCQI is transmitted using a RACH preamble.
 48. The WTRU of claim 47wherein a plurality of signature sequences are divided into a pluralityof groups, and the WTRU selects one group based on the CQI and randomlyselects a signature sequence among signature sequences in the selectedgroup for transmitting the RACH preamble.
 49. The WTRU of claim 47wherein the CQI is appended to the RACH preamble.
 50. The WTRU of claim49 wherein a WTRU identity is appended to the RACH preamble.
 51. TheWTRU of claim 46 wherein the CQI is transmitted via at least one of acontrol part of an RACH message or a data part of the RACH message. 52.The WTRU of claim 51 wherein at least one value of a transport formatcombination index (TFCI) field is reserved for the RACH message thatcontains a CQI, so that a Node-B may distinguish a RACH transmissionincluding the CQI from a RACH transmission not including the CQI. 53.The WTRU of claim 46 wherein the CQI is transmitted along with a RACHmedium access control (MAC) service data unit (SDU).
 54. The WTRU ofclaim 53 wherein the CQI is signaled from a physical layer to a MAClayer via a PHY-Status-IND primitive.
 55. The WTRU of claim 46 wherein aset of signature sequences are reserved for transmitting the CQI via theRACH, so that a Node-B may distinguish a RACH transmission including theCQI from a RACH transmission not including the CQI.
 56. The WTRU ofclaim 46 wherein a set of channelization and scrambling codes arereserved for transmitting the CQI via the RACH, so that a Node-B maydistinguish a RACH transmission including the CQI from a RACHtransmission not including the CQI.
 57. The WTRU of claim 46 whereintransmission of the CQI via the RACH is configured by higher layersignaling.
 58. The WTRU of claim 45 wherein the measurement used forgenerating the CQI is at least one of a measured block error rate(BLER), a path loss on a downlink reference channel, a signal-to-noiseratio (SNR) measured on the downlink reference channel, common pilotchannel (CPICH) Ec/N0, the number of random access channel (RACH)preamble ramp-ups required for RACH transmission, or a received power onthe downlink reference channel.
 59. The WTRU of claim 45 wherein the CQIis an encoded version of at least one of a transport block size or amaximum data rate that the WTRU can support to maintain a target blockerror rate (BLER).
 60. The WTRU of claim 45 wherein the CQI is arelative up/down command.
 61. The WTRU of claim 60 wherein the relativeup/down command is generated based on at least one of a transport blocksize or a maximum data rate that the WTRU can support to maintain atarget block error rate (BLER).
 62. The WTRU of claim 45 wherein theWTRU transmits the CQI periodically.
 63. The WTRU of claim 62 whereinthe CQI is sent with a random offset to reduce probability of collisionbetween WTRUs.
 64. The WTRU of claim 45 wherein the WTRU transmits theCQI in response to a downlink transmission from a Node-B.
 65. The WTRUof claim 64 wherein the Node-B uses a low modulation and coding scheme(MCS) for the downlink transmission.
 66. The WTRU of claim 64 whereinthe Node-B transmits no data on the downlink transmission.
 67. The WTRUof claim 45 wherein the WTRU transmits the CQI on a condition that theWTRU successfully decodes high speed shared control channel (HS-SCCH)transmission.
 68. The WTRU of claim 67 wherein the WTRU sends the CQIvia a radio resource control (RRC) measurement report.
 69. The WTRU ofclaim 45 wherein the WTRU transmits the CQI on a condition that a changeof channel condition exceeds a predetermined threshold for apredetermined period of time.
 70. The WTRU of claim 45 wherein a CQIrange is divided into multiple CQI levels with CQI thresholds, and theCQI is sent on a condition that the CQI crosses a CQI threshold andremains at a new CQI level for a predefined period of time.
 71. The WTRUof claim 45 wherein the WTRU transmits the CQI on a condition that theCQI is in a certain region of CQI statistics.
 72. The WTRU of claim 45wherein the WTRU transmits the CQI based on control information receivedfrom a Node-B.
 73. The WTRU of claim 72 wherein the control informationis transmitted to the WTRU via at least one of a high speed sharedcontrol channel (HS-SCCH), a medium access control (MAC) header, aphysical layer signaling, a layer 2 control signaling, a connectionsetup message, or a broadcast control channel (BCCH).
 74. The WTRU ofclaim 45 wherein the CQI is sent via a radio resource control (RRC)message at an RRC layer.
 75. The WTRU of claim 74 wherein the CQI isfiltered at the RRC layer.
 76. The WTRU of claim 45 wherein the CQI hasa multi-tiered structure so that a coarse CQI and a fine CQI areseparately transmitted.
 77. The WTRU of claim 76 wherein the coarse CQIis sent via a radio resource control (RRC) message and the fine CQI issent via a physical layer (L1) signaling.
 78. The WTRU of claim 45wherein the CQI is sent at a start of a high speed downlink packetaccess (HSDPA) connection in a Cell_FACH state.
 79. The WTRU of claim 45wherein the CQI is sent on a condition that the WTRU changes to aCell_FACH state.
 80. The WTRU of claim 45 wherein the CQI is sent inresponse to cell reselection on a condition that the WTRU a Cell_FACHstate, a Cell_PCH state, or a URA_PCH state.
 81. The WTRU of claim 45wherein the CQI is sent on a condition that the WTRU fails to decode adownlink transmission.
 82. The WTRU of claim 81 wherein a CQI reportingrate is adjusted based on negative acknowledgement (NACK) and positiveacknowledgement (ACK) counts.
 83. The WTRU of claim 45 wherein the CQIis sent on a condition that no data or control information is receivedwhen such is expected.
 84. The WTRU of claim 45 wherein the CQI is sent,in response to correctly decoding a high speed shared control channel(HS-SCCH) transmission, on a condition that the WTRU is not able torecover a high speed physical downlink shared channel (HS-PDSCH)transmission.
 85. The WTRU of claim 45 wherein the CQI is sent inresponse to unsuccessfully decoding a high speed shared control channel(HS-SCCH) transmission K times in an observation window.
 86. The WTRU ofclaim 45 wherein the CQI is sent in response to correctly decoding ahigh speed shared control channel (HS-SCCH) transmission and recoveringa packet on a high speed physical downlink shared channel (HS-PDSCH) inresponse to L retransmissions.
 87. The WTRU of claim 45 wherein the CQIis sent on a condition that the WTRU fails to receive any high speeddownlink packet access (HSDPA) transmission for a predetermined periodof time in response to decoding a high speed shared control channel(HS-SCCH) transmission.
 88. The WTRU of claim 45 wherein the WTRUchanges parameters for sending the CQI autonomously based on radioresource control (RRC) and radio link control (RLC) positiveacknowledgement (ACK)/negative acknowledgement (NACK) information.